1. Field of the Invention
The present invention relates to a method and apparatus for feeding of strip or band material to working machines in which the material is worked upon and split up in individual parts. In particular, the invention is for feeding of metal bands to presses for bending, punching and cutting.
2. Description of Related Art
Feeding of material is preferably by a roll feeder at which the material is brought forward by two rolls between which the material is clamped. The rolls operate intermittently so that feeding of material takes place only when the working machine is in a position for receiving the material. Controllable parameters are stops and starts, rate of feeding and length of feeding.
The roll feeders are usually connected to a working machine, for example an eccentric press, hydraulic press or the like. These are often automated and continuously working machines as it is a requirement that the feed in fully agrees with the speed of operation and need for material of the working machine at each individual moment of operation, the feed in has to be synchronised with the working machine. The roll feeder should not feed material at a higher speed than the process requires as unnecessarily high speed brings with it raised standards of the included components and a greater wear than the correctly adjusted speed. If optimal synchronised operation shall be possible then the roll feeder shall feed the material slowly when the working machine runs slowly and when it works fast the roll feeder shall feed fast. Roll feeders which are under forced control by a mechanical connection with the working machine, for example the eccentric shaft of a press, follow the speed of the working machine but there are great difficulties at the setting of the feed length at a continuous or long material.
One aspect of the present invention is a method and apparatus at which the feed rate of a material feeding device, for example a roll feeder, automatically adjusts itself relative to the speed of the working machine.
The invention will below be described more in detail with reference to the enclosed figure.